National Hydrography Dataset (NHD) Points

Abstract

NHD Points represents hydrographic landmark point features.

Purpose

The NHD was created to assist scientists in modeling hydrologic features and is also
useful for cartographic mapping purposes. The geometric features that came from the
USGS DLG files, combined with the flow direction, reach codes, and other attributes
taken from the EPA RF3 file, make the NHD a powerful modeling tool.

Place Keywords

Source Scale

Horizontal Accuracy

Vertical Accuracy

If the source for elevation is 7.5 minute topo map, estimated to be one half of a contour, or +/- 2.5 feet.

Process Steps

Format

ESRI File Geodatabase

Format Details

Projection

Albers Florida HARN

Field Names

permanent_identifier = Unique ID

fdate = Date of last feature modification.

resolution = Source resolution. All values = 2

Code

Description1

Description2

1

Local

>1:12,000

2

High

1:24,000/12,000

3

Medium

1:100,000

gnis_id = USGS Geographic Names Information System (GNIS) ID

gnis_name = USGS Geographic Names Information System (GNIS) Name

areasqkm

elevation = Feature elevation (Integer)

reachcode = Unique identifier composed of two parts. The first eight digits
is the subbasin code as defined by FIPS 103. The next six digits are randomly assigned,
sequential numbers that are unique within a subbasin, length 14.